You should try counting from the first day of your period until you get it again the following month. It sounds like you need to figure how long your cycles are first. After that, you can estimate when you will ovulate and when your next period will arrive, if your cycles are pretty regular.
An egg is released from one of your ovaries when you are ovulating, this is around 12-16 days before the start of your next period.
7 -10 After conception is when a result can be picked up on a pregnancy test, depending on which pregnancy test you use.
Your period may come, it could be delayed with stress or anxiety. Just give it time & see what happens.